# -*- coding: utf-8 -*-
"""
    flask_marshmallow.sqla
    ~~~~~~~~~~~~~~~~~~~~~~

    Integration with Flask-SQLAlchemy and marshmallow-sqlalchemy. Provides
    `ModelSchema <marshmallow_sqlalchemy.ModelSchema>` classes that use the scoped session
    from Flask-SQLALchemy.
"""
from flask import url_for, current_app
from six.moves.urllib import parse

import marshmallow_sqlalchemy as msqla
from marshmallow.exceptions import ValidationError
from .schema import Schema

class DummySession(object):
    """Placeholder session object."""
    pass

class SchemaOpts(msqla.ModelSchemaOpts):
    """Schema options for `~flask_marshmallow.sqla.ModelSchema`.
    Same as `marshmallow_sqlalchemy.SchemaOpts`, except that we add a
    placeholder `DummySession` if ``sqla_session`` is not defined on
    class Meta. The actual session from `flask_sqlalchemy` gets bound
    in `flask_marshmallow.Marshmallow.init_app`.
    """
    session = DummySession()

    def __init__(self, meta, **kwargs):
        if not hasattr(meta, 'sqla_session'):
            meta.sqla_session = self.session
        super(SchemaOpts, self).__init__(meta, **kwargs)

class ModelSchema(msqla.ModelSchema, Schema):
    """ModelSchema that generates fields based on the
    `model` class Meta option, which should be a
    ``db.Model`` class from `flask_sqlalchemy`. Uses the
    scoped session from Flask-SQLAlchemy by default.

    See `marshmallow_sqlalchemy.ModelSchema` for more details
    on the `ModelSchema` API.
    """
    OPTIONS_CLASS = SchemaOpts

class HyperlinkRelated(msqla.fields.Related):
    """Field that generates hyperlinks to indicate references between models,
    rather than primary keys.

    :param str endpoint: Flask endpoint name for generated hyperlink.
    :param str url_key: The attribute containing the reference's primary
        key. Defaults to "id".
    :param bool external: Set to `True` if absolute URLs should be used,
        instead of relative URLs.
    """
    def __init__(self, endpoint, url_key='id', external=False, **kwargs):
        super(HyperlinkRelated, self).__init__(**kwargs)
        self.endpoint = endpoint
        self.url_key = url_key
        self.external = external

    def _serialize(self, value, attr, obj):
        key = super(HyperlinkRelated, self)._serialize(value, attr, obj)
        kwargs = {self.url_key: key}
        return url_for(self.endpoint, _external=self.external, **kwargs)

    def _deserialize(self, value, *args, **kwargs):
        if self.external:
            parsed = parse.urlparse(value)
            value = parsed.path
        endpoint, kwargs = self.adapter.match(value)
        if endpoint != self.endpoint:
            raise ValidationError(
                (
                    'Parsed endpoint "{endpoint}" from URL "{value}"; expected '
                    '"{self.endpoint}"'
                ).format(**locals())
            )
        if self.url_key not in kwargs:
            raise ValidationError(
                'URL pattern "{self.url_key}" not found in {kwargs!r}'.format(**locals())
            )
        return super(HyperlinkRelated, self)._deserialize(kwargs[self.url_key], *args, **kwargs)

    @property
    def adapter(self):
        return current_app.url_map.bind('')
